1. Field of the Invention
The present invention relates to an air injection and removal system. More specifically, the present invention relates to an insulated apparatus for injecting and removing compressed air from a cooled mold cavity.
2. Background of the Invention
Blow-molded plastic containers have become commonplace in packaging beverages, such as juice, and other hot and cold liquid products. Such a container normally has a dome, an annular sidewall extending from a base, and a waist connecting the dome to the sidewall. Typically, the containers have a horizontal cross section which is circular, rectangular or multi-faceted. Blow-molded plastic containers can provide a package with sufficient flexure to compensate for pressure and temperature, while maintaining structural integrity and aesthetic appearance. In addition, the plastic used in the containers is recyclable.
In a blow-molding process, a parison is inserted into the mold cavity, a needle is inserted into the parison, and the container is blown. In order to keep the mold cool to cool the mold cavity, the mold has passages filled with chilled water. During the blow-molding process, polymer volatiles are generated, and these polymer volatiles need to be vented. If the blow cylinder body block and the needle are not kept at a temperature that is higher than the mold, the polymer volatiles will condense on the needle and the passage inside the needle. Therefore, there is a need for an apparatus to keep the blow cylinder body block and the needle at a higher temperature than the mold to avoid premature condensing of polymer volatiles exhausting through the needle.
According to a first embodiment, an apparatus, mounted to a mold, for injecting air into a mold cavity and removing exhaust from the mold cavity, comprises a blow cylinder body block mounted to the mold having a conduit to the mold cavity, wherein the blow cylinder body block comprises a first insulator and the conduit has walls; a needle passing through the blow cylinder body block and the conduit, wherein the needle is connected to a piston, wherein the needle has a needle passage, and wherein compressed air is applied to the piston to extend the needle into the mold cavity and retract the needle from the mold cavity; and a second insulator between the needle and the conduit walls. The first insulator may comprise Delrin(copyright). The second insulator may be air. The apparatus further comprises a plurality of O-rings surrounding the needle to seal off air flow and exhaust. The apparatus further comprises a groove surrounding the needle in the blow cylinder body block. The apparatus further comprises a cylinder block; and a endcap, wherein the endcap, cylinder block and blow cylinder body block form a housing in which the piston is housed. The cylinder block and end cap comprise aluminum. The apparatus further comprises a first fitting connected to the housing through the endcap; a second fitting connected to the housing through the blow cylinder body block; and a third fitting passing through the blow cylinder body block and connected by an air passage to the needle. The first, second, and third fittings are coupled to a pneumatic drive for supplying compressed air to the first, second, and third fittings.
According to a second embodiment an apparatus, mounted to a mold, for injecting air into a mold cavity and removing exhaust from the mold cavity, comprises a blow cylinder body block mounted to the mold having a conduit to the mold cavity, wherein the conduit has walls; a needle passing through the blow cylinder body block and the conduit, wherein the needle is connected to a piston, wherein the needle has a needle passage, and wherein compressed air is applied to the piston to extend the needle into the mold cavity and retract the needle from the mold cavity; and a first insulator forming a layer on the conduit walls. The apparatus further comprises a second insulator between the first insulator and the conduit walls, wherein the second insulator is air. The apparatus further comprises a plurality of O-rings surrounding the needle to seal off air flow and exhaust. In the second embodiment the blow cylinder body block comprises aluminum. The first insulator may comprise Delrin(copyright). The apparatus further comprises a groove surrounding the needle in the blow cylinder body block. The apparatus further comprises a cylinder block; and a endcap, wherein the endcap, cylinder block and blow cylinder body block form a housing in which the piston is housed. The apparatus further comprises a first fitting connected to the housing through the endcap; a second fitting connected to the housing through the blow cylinder body block; and a third fitting passing through the blow cylinder body block and connected by an air passage to the needle. The first, second, and third fittings are coupled to a pneumatic drive for supplying compressed air to the first, second, and third fittings. In the second embodiment, the blow cylinder body block, cylinder block and endcap comprise aluminum. Alternatively, in a third embodiment, the blow cylinder body block comprises an insulator. The insulator may comprise Delrin(copyright).
According to a fourth embodiment, an apparatus, mounted to a mold having a mounting surface, for injecting air into a mold cavity and removing exhaust from the mold cavity, comprises a spacer; a blow cylinder body block mounted to the mold through a spacer forming an air gap between the mounting surface and the blow cylinder body block, wherein the mold has a conduit to the mold cavity and wherein the conduit has walls; a needle passing through the body and the conduit, wherein the needle has a needle passage, and wherein compressed air is applied to the piston to extend the needle into the mold cavity and retract the needle from the mold cavity; and an insulator between the needle and the conduit walls. The insulator is air. The apparatus further comprises a plurality of O-rings surrounding the needle to seal off air flow and exhaust. The apparatus further comprises a groove surrounding the needle in the blow cylinder body block. The apparatus further comprises a cylinder block; and a endcap, wherein the endcap, cylinder block and blow cylinder body block form a housing in which the piston is housed. The apparatus further comprises a first fitting connected to the housing through the endcap; a second fitting connected to the housing through the blow cylinder body block; and a third fitting passing through the blow cylinder body block and connected by an air passage to the needle. The first, second, and third fittings are coupled to a pneumatic drive for supplying compressed air to the first, second, and third fittings. The blow cylinder body block, cylinder block, and end cap comprise aluminum. The air gap is at least 0.03 inches.